95 A major international review has raised concern over the sharp increase in bowel cancer cases among adults under 50, with researchers pointing to poor dietary habits and imbalanced gut bacteria as key contributors. Once considered a condition largely affecting older adults, early-onset colorectal cancer is now on the rise globally. According to researchers, this increase has been especially marked among those born between 1981 and 2009, with lifestyle changes over recent decades playing a central role. Obesity, sedentary behaviour and the growing dominance of Westernised diets are suspected to be among the leading drivers of this shift. The study, published in EMBO Molecular Medicine, highlights a particular concern with the rising intake of sugary drinks, red and processed meats, and high-fat foods. These have all been found to influence the composition of gut microbes, creating an environment in the intestine that may be more prone to tumour development. A corresponding decline in the consumption of dietary fibre, vegetables, and beneficial nutrients such as calcium, folate and vitamin D is also playing a role. Researchers found that early-onset colorectal cancer presents differently from cases in older adults. It often appears more aggressive, with a tendency to develop on the left side of the colon, and is frequently diagnosed at a more advanced stage. These factors contribute to worse outcomes for younger patients and raise the urgency of understanding and addressing the causes behind the trend. The study also draws attention to the role of the gut microbiome, a diverse ecosystem of bacteria, fungi and viruses that reside in the gastrointestinal tract. Disruptions in this ecosystem, a phenomenon known as gut dysbiosis, have increasingly been associated with inflammation and cancer. A healthy gut microbiome, on the other hand, may offer protection through its ability to regulate inflammation, enhance immune function and even suppress the growth of cancerous cells. Some microbes, such as Lactobacillus gallinarum, Streptococcus salivarius, and Clostridium butyricum, appear to help reduce tumour growth or inhibit inflammation. However, others like Akkermansia muciniphila and Ruminococcus bromii, while generally associated with good gut health, have been paradoxically found in higher levels in some early-onset bowel cancer cases. This suggests that context matters, and the presence of certain microbes may have different effects depending on the broader microbial environment. In addition to bacteria, beneficial fungi such as Saccharomyces cerevisiae and viruses called bacteriophages also play a part in shaping gut health. These non-bacterial components are less studied but may offer new possibilities for prevention or therapy. Researchers are now calling for more targeted investigations into how diet can be adjusted to maintain a healthier gut environment from an earlier age. They argue that with the continued global rise of early-onset colorectal cancer, prevention must begin long before screening typically starts at age 50.